Step 1 : Go to the Terminal ( Applications->Accessories->Terminal ) and type sudo gedit /etc/NetworkManager/nm-system-settings.confStep 2 : A window would now popup displaying the contents of the nm-system-settings.conf fileStep 3 : Now Change "managed=false" to "managed=true"Step 4 : Save the file and close the windowStep 5 : Now back in the terminal type sudo killall nm-system-settingsStep 6 : Thats it, your network interface should now be detected and it should attempt to connect to a network.

Note: Step 5 did not work for me as I got an error "process nm-system-settings not found". So I just restarted my system and my Wi-Fi is working fine again.